#joinlocal

A -joinlocal second instance connects to whichever process holds the loopback port 127.0.0.1:55333, so the precondition to check is socket ownership, not which editor is in play mode.

A -joinlocal second instance never runs the in-game Join UI: it connects straight to the editor's loopback dev-host socket, so it presents an empty invite code. Any host that verifies the code on the wire will correctly reject it, breaking the local two-peer test even though every other hop is healthy. It's a harness artifact, not a product bug.

Networking.HostStats and Connection.Stats read zero on a local loopback two-instance session, including Ping and ConnectionQuality, so a bandwidth instrument built on those fields latches zero even while traffic flows. Count bytes at the application layer instead.